Research subject. The author suggests a new geologic and genetic model for alkaline magmatism. This model considers the saline complexes that are located along the paths of ascending deep magmas as additional sources of alkaline and volatile components. An analysis of the geological and genetic probability of the participation of salts in alkaline magmatism is based on the study of the space-time relationships of natural salts and alkaline magmatic complexes performed using global and regional data. This problem is investigated in a series of three articles. The first article was devoted to characterization of geological prerequisites and their tectonic types. This article sets out to describe the geological aspects of salt-magmatic interactions in greater detail. To this end, the standard alkaline-salt associations of three tectonic types - Italian (cover-fold type), Upper-Rhine (rift type) and North-West-African (passive-margin type) - were characterized.

Methods. The most significant tectonic, lithological and petrological features of all the aforementioned types were described, along with the evolution of space-time relationships of alkaline magmatic complexes. The features confirming the participation of saline complexes in alkaline magmatism were generalized.

Results. It is found that the presence of salt-bearing strata in deep zones of the Earth’s crust along the ascending routes of mantle magmas is a geological phenomenon. The places of their intersection are favourable for the injection of hot magmas and the formation of interstitial chambers, which form centres for interaction between these magmas and the components of saline (salt-carbonate) complexes. The assimilation of the alkaline and volatile components localized in these complexes can contribute to the formation of highly enriched (supersaturated) melt mixtures and a subsequent alkaline specialization of the magmas.

Conclusion. On the basis of the data obtained, a geological model of salt-magmatic interactions has been developed. The author’s next article will discuss the genetic aspects of the proposed model along with a possible role of various alkaline and volatile halophilic components in the formation of alkaline magmas. In addition, a comparative analysis of various geological and genetic models of alkaline pet-rogenesis will be provided.

Research subject. The Kazakhstan (Kazakh-Kyrgyz) paleocontinent attracts much research attention. In this article, we present data on the tectonic structure of the Early Paleozoic Kokchetau-Issykkul sialic terrain.

Materials and methods. The geodynamic position of the Kokchetau-Issykkul terrain was determined by analysing samples of Ordovician rocks collected across 11 sites using the paleomagnetism method. Thus, we studied the paleomagnetism of red sandstones, siltstones, tuffaceous siltstones and basalts, as well as that of andesite and tuffaceous rocks in marine sediments, which affiliation to different Ordovician formations was established on the basis of trilobite, brachiopod, conodont and graptolite fauna.

Results. Early Paleozoic rocks are exposed in the northern part of the studied terrain (Kokchetau district) and in the Issyk-Kul region, which covers southern Kazakhstan, northern Kyrgyzstan and western Xinjiang. The sutures of Chistopol-Terskei and Iradir-Ili ocean basins serving as the boundaries of the Kokchetau-Issykkul terrain are located in the allochthonius position. A multi-storey system of napes composed of pre-Paleozoic and Early Paleozoic rocks of the oceanic crust, volcanic oceanic island arcs and continental slope were studied near the Terskei margin of the terrain. This system of napes is covered by sediments containing graptolites of the Floian-Darriwilian age. Subduction-related volcanism near this margin of the terrain is of the Darriwilian and Sandbian age, while I-type granites are of the Darriwilian age. The over-thrusting of the Iladyr-Ili oceanic crust on the Ili border of the terrain also occurred in the middle Ordovician. Subduction-related mag-matism occurred here in the Late Darriwilian and Sandbian periods.

Conclusion. The conducted studies testify to the geodynamics of the region. In the Early and Middle Ordovician, the Kokchetau-Issykkul terrain was a sialic volcanic arc separated from other sialic terrains by ocean basins. In the Middle Ordovician, the counter subduction of the oceanic crust under the Kokchetau-Issykkul island arc occurred. This process led to the closure of the Chistopol-Terskei and Iradir-Ili ocean basins in Middle Ordovician and to the formation the Kazakhstan continent by the collision of the Early Paleozoic sialic terrains and oceanic island arcs. According to the study of the paleomagnetism of Ordovician rocks in the Kokchetau-Issykkul island, the position of the middle part of this arc is determined to be at the paleogeographic latitude of 9.1 ± 5.4°.

Research subject. In this research, we carried out a series of mineralogical, petrological and geochemical studies to investigate ore zones present in the Kusa ilmenite-magnetite deposit located within the boundaries of a similarly-named laminated gabbro massif. Here, ore bodies occur at various intrusion horizons among laminated apogabbroid amphibolites of a different basicity. In the intrusion section, the composition of halogens (Cl, F) in co-existing fluid-bearing minerals (apatite, am-phibole, staurolite) was analyzed.

Materials and methods. In order to investigate the composition of mineral samples, their polished sections were examined using an electronic-microprobe analyzer JXA-5. The content of petrogenic and microelement components (CRF and ICP-MS methods) in the rock and ore samples was determined using the facilities of the Laboratory of Physical and Chemical methods, UBRAS Institute of Geology and Geochemisty.

Results. It is established that the content of Cl and F in the apatite, amphibole and staurolite under study, as well as the chemical composition of ilmenite, magnetite, and hombombite components, depend on the position of the ore bodies in the intrusion. Thus, the apatites from the near-ore rocks in the central part of the deposit showed the highest Cl concentrations of up to 4.1%, while those located in the near-contact parts of the intrusion demonstrated a much lower Cl content of 2%. The central ore-bearing zone having the maximal Cl content features the largest formation of ore bodies, which (including magnetite) contain higher amounts of Fe₂O₃, Cr and V The presence of fluid-bearing minerals (apatite, scapolite, etc.) with high chlorine concentrations of up to 2.44% is this deposit is established.

Conclusions. The identified peculiarities of halogen distribution in the apatite of bipyroxene gabbro, as well as the inheritance of relations TiO₂/FeO in bipyroxene gabbro, in massive magnetite-ilmenite ores and in near-ore rocks point to a single magmatic source of these formations.

Research subject. This article is devoted to the geochemistry of manganese deposits referred to the Devonian paleovolcanic complexes of the Magnitogorsk belt in the Southern Urals.

Materials and methods. A series of studies was conducted using materials collected from the Kyzyl-Tash, Kazgan-Tash, Kozhayevskoye, Bikkulovskoye and Southern Fayzuinskoye deposits. The content of main elements and rare-earth elements was determined using the X-ray spectral fluorescent and ICP-MS methods, respectively.

Results. It is shown that the values of indicator lithochemical modules in the manganese rocks under study are comparable to those in the modern metal- and ore-bearing sediments. The manganese rocks are characterized by low concentrations of rare-earth elements, as well as by a negative Ce anomaly (Ce/Ce* = 0.20-0.85) in their spectrum and an insignificant prevalence of heavy lanthanides over light ones. In terms of the REE spectrum configuration, the rocks under study are close to modern ferromanganese deposits of a hydrothermal genesis.

Conclusion. The most probable source of Li, Be, Sc, Cr, Rb, Zr, Nb, Hf and Th in the manganese deposits was the detrital material of background sediments. Co, Ni, Ge, As, Mo and Sb, which concentration in the studied rocks is higher compared to that in the detrital component, are most likely to have been produced by hydrothermal solutions. Other rare elements could have been brought into the sediments through different routes. In general, according to the distribution of main, rare and rare-earth elements, the manganese rocks in the Southern Urals are comparable to the deposits of low-temperature hydrothermal sources, which developed within the arc system of the modern ocean. Our findings agree well with the concept of the hydrothermal-sedimentary origin of manganese deposits in the Southern Urals, thus supplementing this hypothesis by the data obtained using independent sources.

Research subject. The article presents the results of a study of a new meteorite Northwest Africa 11781.

Material and methods. The material for the study was a fragment of a meteorite weighing 15.56 g, from which 4 transparent polished sections with a total area of 10.5 cm² were produced. The mineralogy and structural features of the meteorite were studied using a scanning electron microscope JSM-6390LV by JEOL, an electron probe microanalyzer Cameca SX-100 and a quadrupole mass spectrometer with inductively coupled plasma ELAN 9000. All analyses were performed in core facilities “Geoanalytic” IGG UB RAS.

Results. The meteorite is CM2 carbonaceous chondrite comprising ≈ 20-30% of chon-drules and 60-70% of a fine-grained matrix. Refractory inclusions (CAI, AOAs, forsterite rich objects) occupy no more than 3-5%. The average chondrule size is 0.3 mm. Porphyritic olivine (PO) and olivine-pyroxene (POP) chondrules predominate. The meteorite matrix consists of layered silicates and iron hydroxides. CAIs are small in size (0.05-0.3 mm). The main minerals of CAIs are spinel, Ca-pyroxene, hibonite and perovskite. Olivone in AOAs mainly contains spinel-diopside inclusions. The forsterite-rich object presents a low-Fe forsterite with a low-Fe enstatite margin. The meteorite also features an unusually large (1 mm) forsterite-rich object. This object has a transitional position from refractory forsterite to magnesian chondrules. Unusual isolate crystals of high-Fe (FeO 15.35-38.89 wt %) olivine were identified in the meteorite matrix. The mechanism of their formation remains controversial.

Conclusion. It is established that the discovered fragment is a carbonaceous chondrite, therefore being a meteorite that has not been studied before. The meteorite has been recorded as a new carbonaceous chondrite called Northwest Africa 11781 (NWA 11781). The meteorite shows no signs of a shock impact and demonstrates a high grade of terrestrial weathering.

Research subject. In this research, we studied lenses, nodules and interlayers of granulated quartz, which are located in amphibolites and shales in the eastern part of the Ufalei gneso-amphibolite complex.

Materials and methods. Petrographic features of the quartz bodies from garnet-mica, two-mica, garnet-mica and tourmaline-garnet-mica schists and amphibolites were studied using optical spectroscopy on an Axiolab, Olympus BX50 misrospope. The surface morphology of quartz chips was examined using a Tescan Vega 3 Sbu scanning electron microscope equipped with an Oxford Instruments X-act energy dispersive spectrometer. The elemental composition of the initial and deeply enriched quartz concentrates was determined using a Varian-720-ES optical emission spectrometer with inductively coupled plasma. IR spectra were recorded by a Nicolet-6700 Thermo Scientific infrared Fourier spectrometer. The spectra were simulated by superposition of Gaussian lines using the Peakfit program. The surfacing of quartz glasses from a deeply enriched concentrate was carried out using a modernized GRANAT-2M growth installation under argon atmosphere.

Results. Quartz interlayers, lenses and nodules with a thickness of 0.5—1.0 to 1.5—3.0 m are formed by fine-medium or coarse-grained, transparent or translucent granulated quartz. In most cases, quartz bodies exhibit a heterogeneous structure, being intensely blocked and deformed in some places. The quartz under study is characterized by low concentrations of water-containing defects and impurity elements. When conducting deep enrichment of quartz grains, the results obtained are comparable to Unimin IOTA quartz. High quality characteristics of quartz are determined by the conditions of its formation and recrystallization processes, during which the transport of mineral impurities into the intergranular space occurred.

Conclusions. Lenses, nodules and interlayers of granulated quartz in the eastern part of the Ufalei gnesovo-amphibolite complex are promising raw materials for the production of high-quality quartz concentrates.

Research subject. The article presents results of mineralogical and geochemical investigation of albite-bearing granites with high concentrations of trace elements located in the Western Trans-Baikal region.

Methods. The composition of rocks was determined by the methods of classical silicate analysis, X-ray fluorescence and ICP-MS analysis. Microstructural features, relationships and homogeneity of minerals were studied using an electron microscope LEO-1430 equipped with an energy dispersive spectrometer Inca Energy-300. Isotopic compositions of oxygen were carried out using a mass spectrometer Finigan MAT 253 in the mode of a constant helium flow.

Results. Ore mineralization is specified by the presence of Nb-bearing and less REE-bearing minerals. The studied rocks were divided into two groups: albitized granites, and deep albitized granites and albitites. These groups differ in terms of the presence of accessory minerals. The deep albitized granites and albitites belong to alkaline riebeckite-albite granites containing Nb-, Zr-, Y- and REE-bearing minerals. These rocks contain Y-bearing minerals - thalenite and yttrialite, with an up to 4 wt % inclusion of Y₂O₃ in titanite, chevkinite, thorite and monazite. In contrast, the albitized granites contain fewer amounts of Y and HREE along with LREE-bearing minerals (monazite, allanite, fluocerite, samarskit).

Conclusion. The selected groups of rocks have been analyzed in terms of their mineral and geochemical characteristics. The main Nb-bearing mineral in albitized granites is columbite. Minerals from albitites are rich in Y and HREE. The isotopic investigation has shown involvement of a magmatic-derived fluid in the rock formation process.

Background. Any exploration work involves difficulties associated with a rapid assessment of the development prospects of the discovered ore occurrences, flanks and deep horizons of the exploited fields, new vein bodies within the known ore fields and nodes. Under these conditions, knowledge of the genetic models of formation of gold and crystal mineralization, genetically associated with quartz veins, gains a particular importance.

Aim. There is a widespread opinion that the presence of industrially applicable crystal is characteristic only of barren quartz veins. As a result, it is such formations that attract the interest of researchers searching for deposits of rock crystal. However, a large number of ore minerals have been found in the crystal-bearing quartz-vein deposits in the Urals, both in the vein bodies and in the crystal cavities.

Results. The analysis of a large amount of factual material carried out to reveal regularities of location of quartz-vein formations in the Ural deposits of crystal-like and gold mineralization testifies to the confinement of quartz-vein fields to suture zones, representing narrow extended tectonic ensembles of a complex geological structure, genetically and spatially associated with long-lived faults of deep laying. The formation of quartz veins refers only to certain stages of the deposit development, while the deposits themselves are always confined to certain structural elements. These structural elements determine the subsequent formation of ore fields, which frequently undergo significant transformations.

Background. In this paper, we provide new data on the morphology and geochemistry of heraclites, which are represented by specific products formed by degradation of the carbonate paleostructures of prokaryotes around the degassing zones of the Miocene age. The heraclites exhibiting siltstone and sandstone structures are referred to as micrometanolites. An analysis of literature data showed that heraclites had formed in the upper sedimentary strata under the conditions of increased methane levels in the affinity of the stream exits.

Methods. The geochemical examination of heraclites of a different colour and morphology was carried out using ICP-MS at the facilities of the Geoanalytik centre, UB RAS Institute of Geology and Geochemistry, Ekaterinburg.

Results. According to lithological characteristics and morphology, the following heraclite types were distinguished: slag-like, banded, angular and сementation slabs. Morphologically, the heraclites under study were characterized by high concentrations of Sr, Ba, Co, Ni, Bi, Ce, Nd and Yb, which significantly exceed those in carbonate rocks. The concentrations of Rb, Cs, Nb, Th, Cu, Tl, As, Sc, Sb, Eu, Gd, Tb, Dy and Er in some morphological differences were above the Clarke values, while others demonstrated their deficit. The samples under study showed low concentrations of some heavy REE. A high content of lithophilic, chalcophile, siderophilic and REE elements indicate paleo-fluids of a deep mantle-derived character. The data on the oxide environment during construction material formation was obtained, which is confirmed by low concentrations of U (0.579 to 2.096 ppm) and Bi (0.014-0.084 ppm), as well as the ratios of U/Th (0.4-2.1), V/Cr (0.3-0.9) and Mo/Mn (less than 0.0014). Such conditions existed near or within the cellular organism of prokaryotes. Low concentrations of U, Ti, Mn and Zr confirm a significant growth rate of heraclite carbonate substances. Minor differences in the concentrations of chemical elements in heraclites of a different morphology are believed to have resulted from the physic-geographical and chemical conditions of their formation across the areas of regional faults with an active tectonic regime.

Conclusions. Our results have confirmed the assumption that the carbonate material of heraclites formed by processing of deep fluids. In the South-Western Crimea, heraclites constitute a geological phenomenon of the Miocene hydrocarbon paleo-degassing, which was associated with the neotectonic stage of the uplift of the Crimean Mountains. The presence of methane, ethane, propane and petroleum products in the composition of heraclites allows an assumption to be made about the presence of oil and gas deposits in the Sevastopol region.

Object of research. The mathematical apparatus of the theory of fractals and the algorithms developed within its framework are used to assess the statistical self-similarity of the fields of epicenter earthquakes in the Baikal region.

Materials and methods. The solution is implemented on numerical models and at three hierarchical levels of the lithosphere of the region. A modified method for determining the fractal dimension is applied, when the scaling data are approximated uniformly for territories of various shapes and sizes, subject to the maximum coefficient of pair linear correlation of the function lnN = f(lnr). Numerical implementations of epicentral field models in the form of a “Koch snowflake” and “Sierpinski carpet” confirmed the advantage of the method in conditions of limited data arrays used.

Results. Seismicity reflects the process of fault formation in the lithosphere, and the use of the modified method allows one to obtain more accurate parameters of the state of the fault structure of the lithosphere from the field of epicenters of earthquakes in the Baikal region. The main influence on the assessment of the indicator is provided by two interrelated factors: the growth of instrumental data over time and the geometry of the distribution of earthquake epicenters over the territory. Using the maximum correlation coefficient to estimate the self-similarity of the field of epicenters of earthquakes in the Baikal region allows us to significantly refine the magnitude of the self-similarity index - the difference between the self-similarity index (D₀ ≈ 1.70) and the cell dimension (D₀ ≈ 1.58) significantly exceeds three standard deviations.

Findings. The applied method has a particular advantage with a small amount of initial data and can significantly improve the assessment of the self-similarity index in conditions of a limited duration of instrumental monitoring of earthquakes. In the absence of reliable data on the deep structure of the fault-block geomedium, the approach used and the results obtained contribute to the understanding of modern geodynamics and seismotectonics of the lithosphere of the Baikal region by analyzing the fault structure of the territories through the fractal dimension of the earthquake epicenter fields. In practical terms, information on monitoring the state of the fault structure of the lithosphere according to earthquake data can be used to characterize the seismic situation and the danger in industrial and civil construction areas.